Circuit breaker contact structure



April 9, 1957 c. L. JONES 2,788,421

CIRCUIT BREAKER CONTACT STRUCTURE Filed May 12, 1953 2 Sheets-Sheet lFig.l. 23 23 I H WITNESSESI INVENTOR {.42 7 .91367.

ATTORN Charles L. Jones.

April 9, 1957 c. L. JONES 2,788,421

CIRCUIT BREAKER CONTACT STRUCTURE Filed May 12, 1953 2 Sheets-Sheet 2Fig.2.

w :22 67 45 :46 52 BI 65 INVENTOR Charles L. Jones.

CATTORN Charles L. Jones, Beaver, Electric Corporation, tion ofPennsylvania Application May 12, 1953, Serial No. 354,553 9 Claims. (Cl.269-166) Pa., assignor to Westinghouse East Pittsburgh, Pa, a corpora-This invention relates to circuit breakers and more particularly tocontact structures for air circuit breakers.

This application is a continuation-in-part of my copending applicationSerial No. 305,334, filed August 20, 1952, now abandoned, and assignedto the assignee of the instant application.

An object of the invention is to provide a circuit breaker embodying animproved contact structure of rugged construction and reliable inoperation.

Another object of the invention is to provide a circuit breaker havingan improved contact structure in which the moving contact is looselymounted on the movable switch arm and is provided with means forpreventing lateral tilting movement of the moving contact.

A further object of the invention is to provide a contact structurewhich is compact and small in size for its rather large current rating,and thereby makes possible a reduction in overall size of the circuitbreaker.

Another object of the invention is to provide a multipole circuitbreaker embodying an improved contact structure having simple andreliable means for aligning the moving contacts for the several poles ofthe breaker.

This invention is an improvement on the circuit breaker shown in PatentNo. 2,546,016 or" Jerome Sandin and Ture Lindstrom, issued March 26,1951, by which the overall size of the breaker has been reduced byone-third, with very substantial savings in cost, while at the same timeretaining the maximum normal currentcarrying capacity of the breaker ashigh as 225 amperes at 600 volts A. C.

The invention, both as to structure and operation, together withadditional objects and advantages thereof, will be best understood fromthe following detailed description thereof, when read in conjunctionwith the accompanying drawings.

In said drawings:

Fig. 1 is a top plan view, with the cover partly broken away, of athree-pole circuit breaker embodying the principles or the inventionwith the arc chute removed from the left-hand pole;

Fig. 2 is an elevational sectional view taken substantially along lineII-II of Fig. l and looking in the direction indicated by the arrows;

Fig. 3 is an enlarged sectional view showing the contact structure forthe center pole of the breaker;

Fig. 4 is a perspective view showing the contact structure for one ofthe outer poles of the breaker;

Fig. 5 is a sectional view taken on line V-V of Fig. 3 and looking inthe direction indicated by the arrows; and

Fig. 6 is an end elevational view showing the wrapper for the flexibleconductor.

Referring to Figs. 1 and 2 of the drawings, the multipole circuitbreaker includes a base 11 and a cover 3.3 of molded insulatingmaterial, an operating mechanism indicated generally at 15, and a tripdevice indicated generally at 17. The casing formed by the base 11 andcover 13 is divided into three compartments, each of nited States Patent0 which is adapted to receive a stationary contact 19 and a cooperatingmovable contact 21 which, with their corresponding terminals andconnecting conductors, collectively form the three poles of the breaker.Each pole of the circuit breaker is provided with end terminals 23disposed in suitable openings formed in the base 11 at each end thereof.

The terminals 23 are 24 which are preferably suitably secured to metalinserts loosely mounted in the end portions of the base, as in theapplication of L. W. Dyer and C. L. Jones, Serial No. 294,229, filedJune 18, 1952, and assigned to the assignee of this application. Thestationary contact 19 for each pole is rigidly secured to the inner endof a conductor 25 having its outer end suitably secured to the adjacentterminal 23. The conductor 25 is secured tothe base 11 by means ofscrews 27 (Fig. 1) which also secures an arc runner 29 to the conductor25 adjacent the stationary contact 19. i

The are runner 29 comprises a folded metallic member having sideportions 313 (Fig. 1) which are secured to the base 11 by the screws 27and a sheet of insulating material 31 which is inserted between theupper and lower portions of the runner for covering the side portions30.

An arc extinguisher 32 is'previded for each pole of the breaker andcomprises a stack of slotted plates 34 of magnetic material positionedadjacent the path of movement of the movable contacts 21. The presenceof these plates causes the are drawn upon separation of the contacts tobe drawn into the apexes of the slots where the arc is broken up andextinguished. The provision of the piece of insulation 31 covering theside portions of the arc runner prevents the are from travelling alongthese side portions and striking the side of the lowest plate 34 of thearc extinguisher.

The movable contact structure are the same, for which reason only theone for the center pole will be described. Mounted in the centercompartment and secured to the base 11 is a U-shaped frame 35 whichsupports the operating mechanism for the circuit breaker. Pivotallymounted in the frame 35 by means of a pivot pin 37 supported in the sidemembers of the frame 35 is a channel-shaped switch member 39 of steel orlike material upon which is mounted the moving contact structure.

The moving contact structure comprises a contact member 41 of a goodconducting material such as copper or a cupreous alloy to which isbrazed or otherwise suitably secured the moving contact 21 which, likethe stationary contact 19, is of a good-conducting arcresisting materialsuch as silver-tungsten or silvermolybdenum. The outer end of thecontact member 41 is turned upwardly at 41' to form an arc runner orhorn. Also secured to the contact member 41 by means of a countersunkrivet 42 and disposed on the side opposite the contact 21 is a steelsupport member or bracket 43, the upper portion of which is providedwith a T-shaped opening 45 (Figs. 3, 4 and 5) through which extends end47 of the switch member for the several poles the reduced and notched 39providing a removable lost-motion connection between the switch memberand the contact member. In order to prevent turning movement between thebracket 43 and the contact member 41, pointed portions 44 are struckdownwardly from opposite edges of the steel bracket 43 and are pressedinto the softer copper of the contact member 41 during the rivetingprocess, making it possible to use only a single rivet and still obtaina fastening which remains secure after the hammering of many opening andclosing operations.

A coil spring 49 compressed between the switch member 39 and the portionof the support member or bracket 43 which is secured to the contactmember 41 provides contact pressure in the closed position of thebreaker. The upper end 48 of the rivet 42 provides a spring seat for thespring 49, and a spring seat 46 is formed on the switch member 39 by theprocess of embossing. In the open position of the breaker, the spring 49biases the upper end of the opening 45 in the bracket 43 against the topof the end portion 47 of the switch member 39, and also biases theright-hand end 41 (Fig. 3) of the contact member 41 downwardly against arod 51 carried in the side portions of the channel-shaped switch mem ber39.

In order to prevent lateral tilting movement of the contact member 41,and provide a line contact across the heel of the contacts 19 and 21, anangular bracket 57 (Figs. 3 and 4) is secured to the underside of thecontact member 41 adjacent the rod 51 and has an ofl'set portionextending beneath the rod. The bracket 57 is secured to the contactmember 41 by means of embossed portions 59 on the contact memberextending through openings in the bracket and riveted over. The bracket57 and the right end portion 41 of the contact member cooperate with therod 51 to prevent lateral tilting movement of the contact member andprovide a good contact across the width of the contacts 19, 21.

This construction facilitates assembly of the contact member 41 on theswitch arm 39 since the bracket 57 and the tail or end 41" of thecontact member together form a U-shaped slot which is slipped over thepin 51 at the same time that the wide portion of the T-slot 45 isengaged with the reduced end 47 of the switch arm 39 by a motionlongitudinally of the switch arm. The slot and pin connection of thecontact member 41 on the pin 51 permits pivoting of the contact memberabout 51 as a pivot to the extent permitted by the slot 45. The contactmember 41 is of lower cost than the cast contact members formerly usedin breakers of the same current rating and service, since the contactmember 41 is readily punched and formed or stamped from flat copperstock with the arc-horn portion 41' bent up at one end and the tail 41"for supporting it at the other end.

In order to insure simultaneous separation and engagement of the movingcontacts with the stationary contacts for all of the poles, means isprovided to adjust the position of the contact member 41 for one or morepoles relative to the corresponding switch member 39. This meanscomprises shims 52 of different thickness, one or more of which may beinserted in the opening 45 between the top of the switch member 39 andthe bracket 43 and secured to the switch member 39 by means of a screw54. In this manner, the contact member 41 for each of the poles may beadjusted so that the contacts for all the poles break and touchsimultaneously on opening and closing operations, respectively.

The assembly just described with the formed copper contact member 41having the steel bracket 43 secured thereto by the countersunk rivet 42,over the head of which is secured the arc-resisting contact 21, togetherwith the use of the headed-over end of the rivet and the boss 46 forholding the contact pressure spring 49 in place, and the notch and slotconnection between the bracket 43 and the end 47 of the contact arm,with the shims 52 for giving simultaneous make and break of thecontacts, gives the advantages of most efiicient use of the parts tosave materials, low assembly labor, easy removability, ruggedness tostand up during many operations, and compactness to reduce the overallsize of the circuit breaker.

A flexible conductor 53 is mechanically and electrically connected atone end directly to the contact member 41 by welding or brazing. Theother end of the flexible conductor 53 is provided with a metallicWrapper 60 in order to provide a fiat surface and to facilitate punchinga hole therein to receive a screw 61 by which the conductor 53, togetherwith the conductor 55, is secur to the base 11. v

The wrapper 60 is preformed to substantially the shape shown in Fig. 6.As shown in Fig. 6 the wrapper 60 is formed with an arcuate bottomportion 62, side portions 64 and beveled or angular corner portions 66.In practice the edges of the flexible conductor are placed in theangular corners and then the side portions 64 are bent down on top ofthe flexible conductor as shown by dot and dash lines in Fig. 6,providing flat top and bottom portions. The end of the assembly may bebrazed or soldered after which the hole is punched through both thewrapper and the conductor to receive the screw 61.

One end of the flexible conductor 53 is brazed to the contact member 41,and the other end of the flexible conductor is electrically connected toa conductor 55 which extends through the current-responsive trip deviceof the breaker and is finally connected to the terminal 23 at the rightend of the breaker.

A metal tie bar 63 encased in an insulating tube 65 is clamped to thechannel-shaped switch arm 39 by means of a clamp 67 having its endsriveted over on the underside of the switch arm. The tie bar 63 extendsacross all three poles of the breaker, and the switch arms 39 (Figs. 1and 4) for the outer poles are similarly clamped thereto for unitarymovement to open and closed positions. Brackets 69 (Fig. 1) disposed inthe end compartments and secured by means of screws 71 to the base 11have pivot pins 73 (see also Fig. 4) mounted therein in alignment withthe pivot pin 37 (Fig. 2). The pivot pins 73 extend inwardly from thebrackets 69 and pivotally support the switch members 39 for the outerpoles.

The operating mechanism 15 for operating the movable contact structureto open and close the contacts for all of the poles of the breaker issupported between the side members of the U-shaped frame 35 in thecenter compartment of the breaker housing. The operating mechanismcomprises a pair of toggle links 77 and 79 pivotally connected togetherby a knee pivot pin 81. The toggle link 77 is pivotally connected bymeans of the rod 51 to the center pole switch member 39, and the togglelink 79 is pivotally connected by means of a pivot pin 83 to areleasable cradle 85. The releasable cradle 85 is pivotally mounted on apin 87 supported in the frame members 35, and its free end is releasablyengaged by a latch 89 forming a part of the trip device 17.

The toggle 77, 79 is operated to effect opening and closing movement ofthe contact structure by means of a U-shaped operating lever 91 and anovercenter operating spring means 93. The legs of the operating lever 91(only one leg being shown) are pivotally mounted on pins 95 in the sidemembers of the frame 35. The overcenter spring means is connected undertension between the knee pivot pin 81 of the toggle 77, 79 and the bightof the U- shaped operating lever 91. An insulating operating handle 97has side portions 99 which are attached by means of screws (not shown)to the legs of the operating lever 91. The handle 97 extends out throughan opening 102 in the cover 13 and has an arcuate portion 104 integraltherewith which substantially closes the handle opening 102 in allpositions of the handle.

In the closed position of the circuit breaker, the toggle 77, 79 isslightly overset, thus locking the movable contact structure in closedposition against magnetic blowofi action in response to short-circuitcurrents. The overset position of the toggle 77, 79 is determined by theengagement of an arcuate surface 103 (Fig. 3) on the toggle link 77 witha projection 105 on the cradle 85 adjacent the pivot pin 87. Themovement of the operating lever 91 to the closed position is limited byengagement thereof with inwardly formed ears 107 (only one being shown)on the frame member 35.

The circuit breaker is opened by movement of the operating handle 97 ina counterclockwise direction from the position in which it is shown inFig. 2. This movement carries the line of action of the overcenterspring 93 over to the left of the pivot pin 83, whereupon the force ofthe spring 93 causes collapse of the toggle 77, 79 and causessimultaneous opening movement of the movable contact structure to openthe contacts of all of the poles with a snap action. The openingmovement of the movable contact structure is limited by engagement of adepressed portion 106 of the switch arm 39 for the center pole with thepivoted end of the releasable cradle 85.

In the closed position of the contacts 19, 21 the movable contact 21 isat a slight angle with respect to the stationary contact 19 so that thecontacts are in engagement at a line across the width of the contacts ata point adjacent the heel of the movable contact as shown in Fig. 3. Asthe switch member 39 moves in opening direction the contact member 41pivots about the pin 51 until the switch member 39 engages the upper endof the slot 45 in the bracket 43. During this movement the pin 51 movesupwardly and the spring 49 causes the contact member 41 to pivot aboutthe pin 51. This causes the movable contact to rock forward on thestationary contact 19 so that the contacts separate at their tipsadjacent the arc runner 29 and the arc horn 41. The reverse movementoccurs when the contacts are closed, that is, the contacts touch attheir tips and the movable contact rocks back to the closed position inwhich it is shown in Fig. 3.

The movable contact structure is operated to the closed position byclockwise movement of the operating handle 97 and the operating lever 91back to the position shown in Fig. 2. This movement of the operatinglever 91 carries the line of action of the spring 93 overcenter to theright of the pivot pin 83, whereupon the force of the overcenter spring93 straightens the toggle 77, 79 and moves the switch members 39 for allof the poles to the closed position to close the contacts with a snapaction.

The circuit breaker is opened automatically in response to overloadcurrents occurring in the circuit of any pole of the breaker, byoperation of the trip device 17. The trip device may be of any suitabletype, preferably of the type disclosed in Patent No. 2,586,326, issuedFebruary 19, 1952, to G. G. Grissinger and Jerome Sandin, and assignedto the assignee of the instant application. Such trip devices areprovided with thermally-responsive means operable to release the latch89 after a time delay in response to overload currents below apredetermined value, and are also provided with electromagnetic meansoperable to instantaneously release the latch 89 in response to overloadcurrents above the predetermined value, or in response to short-circuitcurrents.

When the latch 89 is released by the trip device 17 in response to anoverload current, it frees the cradle 85 and permits the spring means 93to rotate the cradle in a counterclockwise direction about its pivot 87,thus causing collapse of the toggle 77, 79 and movement of the movablecontact structure to open position to thereby open the contacts for allof the poles of the breaker. The contacts cannot be closed following anautomatic opening operation until the cradle 85 has been reset andrelatched. This is accomplished by moving the operating handle 97 as faras it will go in opening direction during which movement a projection109 on the operating lever 91 engages a shoulder 110 on the cradle andmoves the latter clockwise to reengage the free end thereof with thelatch 89. After the cradle 85 has been reset and relatched, the contactsmay be closed by counterclockwise movement of the operating handle 97 inthe manner previously described.

It will thus be seen that the invention provides a circuit breakerhaving an improved compact and low-cost contact structure in which themoving contact carrying member is loosely'mounted on the movable switchmember but is prevented from tilting sidewise. Spring means is disposedbetween the switch member and the moving contact member to providecontact pressure in the closed position of the breaker, and simple,reliable aligning means is provided to align the moving contact membersof the several poles so that the contacts for all of the poles make andbreak simultaneously.

Having described the invention in accordance with the requirements ofthe patent statutes, it is to be understood that various changes andmodifications may be made in the structural details thereof withoutdeparting from some of the essential features of the invention.

I claim as my invention:

1. In a circuit breaker, stationary and movable contacts, a pivotedswitch member having side portions and a. end portion, operating meansoperatively related to said switch member for moving said switch memberto open and close said contacts, a movable contact member having saidmovable contact mounted thereon adjacent one end, a member rigidlysecured to said contact member and having an opening therein forreceiving the reduced end of said switch member to thereby support saidone end of said contact member for limited movement relative to saidswitch member, a support member disposed between the side portions ofsaid switch member for supporting the other end of said contact member,a bracket secured to the other end of said contact member, and having aportion disposed on the side of said support member opposite saidcontact member, said contact member and said bracket cooperating withsaid support member to maintain said contact member and said movablecontact in alignment with said stationary contact, and spring meansdisposed between said switch member and said contact member forproviding contact pressure in the closed position of said breaker.

2. In a circuit breaker, stationary and movable contacts, a movableswitch member having side portions and an end portion, means operativelyrelated to said switch member for moving said switch member to open andclosed positions to open and close said contacts, a contact membersupporting said movable contact, a part riveted to said contact memberand having an opening therein for receiving the end of said switchmember, said part having portions thereon for penetrating said contactmember to prevent said part from turning relative to said contactmember, a pin supported between the side portions of said switch member,an angular member secured to said contact member adjacent the other endthereof, said contact member and a portion of said angular member beingdisposed on opposite sides of said pin to support said contact memberfor limited pivotal movement while preventing lateral tilting movementof said contact member, and a coil spring compressed between said switchmember and said contact member for providing contact pressure when saidcontacts are closed.

3. In a multi-pole circuit breaker having a housing divided into threecompartments, stationary and movable contacts in each compartment, amovable switch member in each compartment, means interconnecting saidswitch members adjacent one end thereof for unitary movement to open andclosed positions, operating means in one of said compartments connectedto move said switch members to open and closed positions, a contactmember in each compartment, a support member rigidly secured to each ofsaid contact members and having an opening therein fitting over theother end of the associated switch member for supporting one end of saidcontact member on its associated switch member for limited movementrelative thereto, a pin mounted on each of said switch members forsupporting the other end of the corresponding contact member, a bracketon each of said contact members, each of said brackets having a portiondisposed on the side of said pin opposite said contact members, saidcontact members and said brackets cooperating with said pins to preventlateral tilting movement of said contact members, spring means betweeneach of said switch members and its associated contact members forproviding contact pressure, and

adjusting means comprising one or more members insertable in one or moreof said openings between said switch members and said support membersfor adjusting one or more of said contact members relative to theassociated switch members so that all of said movable contacts engageand disengage their associated stationary contacts substantiallysimultaneously.

4. In a circuit breaker, stationary contact means, a movable switchmember, movable contact means mounted on said switch member, said switchmember being movable to open and closed positions to open and close saidcontact means, operating means disposed to move said switch member toopen and closed positions, means for attaching one end of said movablecontact means to said switch member for limited movement relativethereto comprising a bracket mounted on said contact means and having anopening therein through which one end of said movable switch memberextends, means for determining the movement of said movable contactmeans relative to said switch member comprising a member insertable insaid opening between said switch member and said bracket, means forsupporting the other end of said movable contact means on said switchmember for pivotal movement relative thereto comprising a support onsaid switch member, and a member mounted on said movable contact meanshaving a portion engaging the side of said support opposite said contactmeans.

5. In a circuit breaker, stationary contact means, a movable switchmember, a movable contact carrying member mounted on said switch memberand having a movable contact thereon, said switch member being movableto open and closed positions to open and close said contacts, operatingmeans operatively related to said switch member for moving said switchmember to open and closed positions, means for attaching one end of saidmovable contact carrying member to said switch member for limitedmovement relative thereto comprising a bracket mounted on said movablecontact carrying member and having an opening therein through which oneend of said movable switch member extends, means for supporting theother end of said movable contact carrying member on said switch memberfor pivotal movement relative thereto comprising a support on saidswitch member engaged by the other end of said movable contact member,and a member mounted on said movable contact carrying member having aportion engaging the side of said support opposite said movable contactcarrying member to prevent excess movement of said contact carryingmember relative to said support.

6. In a circuit breaker, stationary contact means, a movable switchmember, a movable contact carrying member mounted on said switch memberand having a movable contact thereon, said switch member being movableto open and closed positions to open and close said contacts, operatingmeans connected to move said switch member to open and closed positions,means for attaching one end of said movable contact carrying member tosaid switch member comprising a bracket mounted on said movable contactcarrying member and having a lost motion connection with said switchmember, spring means between said switch member and said bracket forproviding contact pressure in the closed position of said switch member,means pivotally supporting the other end of said movable contactcarrying member on said switch member comprising a pin on said switchmember supporting said other end of said movable contact carryingmember, and a member secured to said movable contact carrying member andhaving a portion disposed on the side of said pin opposite said movablecontact carrying member to prevent excess movement of said contactcarrying member relative to said pin. 7 7. In a circuit breaker, apivotally mounted switch arm, a movable contact carrying member of goodconducting material mounted under said switch arm and extendingsubstantially parallel thereto, said movable contact carrying membercomprising a stamping of flat stock formed with an integral arc-hornportion extending outwardly at one end, a bracket fastened to the upperside of said movable contact carrying member adjacent said arc hornportion and having an opening therein through which the end of saidswitch arm extends to form a lost-motion connection, a contact ofarc-resisting contact material mounted on the lower side of said movablecontact carrying member opposite said bracket, a contact pressure springbetween the switch arm and said movable contact carrying member, and atail portion at the other end of said movable contact carrying membersupported on a portion on said switch arm.

8. In a circuit breaker, a pivotally mounted switch arm, a contactcarrying member of good conducting material mounted under said switcharm, said contact carrying member comprising a stamping of flat stockformed with an arc-horn portion extending outwardly at one end, abracket fastened to the upper side of said contact carrying memberadjacent said are horn portion by means of a rivet having a headcountersunk at the lower side of the contact carrying member and havingits other end riveted over at the upper side of said bracket, and saidbracket engaging said switch arm with a lost-motion connection, acontact of arc-resisting contact material positioned on the lower sideof said contact carrying member opposite said bracket and over thecountersunk head of said rivet, a contact pressure spring between theswitch arm and the bracket held in place at one end by a downwardlyextending projection on the switch arm and at the other end by the endof the rivet at the upper side of the bracket, and means on said switcharm supporting the other end of said contact carrying member.

9. In a circuit breaker, a pivotally mounted switch arm, a contactcarrying member of good conducting material mounted under said switcharm, said contact carrying member comprising a stamping of fiat stockformed with an arc-horn portion extending outwardly at one end, abracket fastened to the upper side of said contact carrying memberadjacent said are horn portion and engaging said switch arm with alost-motion connection, a contact of arc-resisting contact materialpositioned on the lower side of said contact carrying member oppositesaid bracket, a contact pressure spring between the switch arm andcontact carrying member, a tail portion at the other end of said contactcarrying member engaging a portion on said switch arm, an integralprojection embossed through the contact carrying member adjacent itstail portion, and an element secured to said tail portion on saidintegral projection and also engaging said portion on the switch arm onthe opposite side from said contact carrying member.

References Cited in the file of this patent UNITED STATES PATENTS1,724,840 Jones et al. Aug. 13, 1929 1,762,604 Ainsworth June 10, 19301,779,659 Carichofl Oct. 28, 1930 2,047,739 Lingal July 14, 19362,165,511 Sandin July 11, 1939 2,288,270 Dorfman et al June 30, 19422,459,588 Sandin et a1. Jan. 18, 1949 2,546,016 Sandin et al. Mar. 20,1951

